The assignee of the present invention manufactures and deploys spacecraft for, inter alia, communications and broadcast services from geostationary orbit. Payload systems of such spacecraft conventionally employ input multiplexers to channelize a radio frequency band of electromagnetic energy into a set of channels by use of a filter bank. The mass, efficiency, cost, and complexity of a multiplexer are important factors in determining the overall performance of the payload system.
A known hybrid coupled multiplexer 100, supporting ‘n’ channels, is illustrated in FIG. 1. For each channel (i), the multiplexer includes a first 90° hybrid coupler 110(i) and a second 90° hybrid coupler 130(i). Disposed in parallel between the first hybrid coupler 110(i) and the second hybrid coupler 130(i) are two substantially identical filters, 121(i) and 122(i). Because each filter handles only 50% of the power per channel, the above-described approach mitigates certain power and voltage handling problems, particularly for high power applications.
Since each channel requires two filters and two hybrid couplers, however, the mass, cost and volume of the device is undesirably large.
As a result, an improved input multiplexer design is desirable.